Magnetic tape drives are generally of the reel to reel type or the tape cartridge type. Magnetic tape cartridge types of magnetic tape drives are becoming a popular backup means for winchester disc drives because of their ease of use and low cost. For magnetic tape cartridge drives to work reliably, the tape cartridge must be accurately held in position by a clamp and eject mechanism.
The primary function of the clamp and eject mechanism is to accept the tape cartridge from a user and to accurately position the tape cartridge in the tape drive. In order to correctly read the information located on the magnetic tape in the cartridge, the cartridge must be positioned with respect to the base of the cartridge. Incorrect positioning leads to read errors and unreliable operation. The clamp and eject mechanism may be activated either by the presence of the cartridge in the mechanism or by other means. The cartridge may be loaded into the clamp and eject mechanism either with the front of the cartridge first, hence front loading, or with the end of the cartridge first, hence end loading.
Quarter inch tape cartridges are typically positioned by the clamp and eject mechanism according to the American National Standards Specification X3.55-1977 For Magnetic Tape Cartridges. According to this standard, the cartridge is positioned with reference to the top of the base of the tape cartridge using a force applied at 45 degrees to the lower front edges of two notches located on each side of the cartridge base. Because of the high variability of tolerances associated with the manufacture of the tape cartridges, it is important that the clamp mechanism properly position both sides of the cartridge in order to prevent errors in locating the information on the magnetic tape. Some prior art drive devices have incorporated an individual dual latching reference mechanism. When these cartridge activated latching mechanisms are used, it is possible for the cartridge to be positioned incorrectly. This occurs when one side of the independent dual latching mechanism latches without the other side of the mechanism latching.
Eject mechanisms used in prior art magnetic tape cartridge drives typically operated independently of the latching mechanism. These eject mechanisms operated by overriding the force associated with the latching mechanism and hence were sometimes difficult for a user to operate. Also many of the prior art eject mechanisms may eject the cartridge while the tape drive is still operating causing undesirable loss of data.
A need exists for a relatively simple combined latch and eject mechanism which guarantees the proper positioning of the cartridge yet is low in cost and reliable.